Skip to main content
Guide to New Zealand's freshwater invertebrates
Single gill mayfly
Deleatidium mayfly nymphs have a flattened body form, single leaf-like gills and a wide labrum (top “lip”).
Deleatidium larvae are the most abundant invertebrates in many fast-flowing, stony-bottom streams with cool and well aerated water, especially in the South Island.
Leptophlebiid mayflies feed by scraping diatom algae and other organic matter from stone surfaces.
High abundances of Deleatidium suggest good habitat and water quality conditions, especially if other mayfly or stonefly groups are abundant. Deleatidium has tolerance values of 8 (hard bottom sites) and 5.6 (soft bottom sites).